In the process of assembling display devices, a frame sealant is attached to a backlight source and then the backlight source with the frame sealant is adhered to other components. The frame sealant is usually manually attached, for example, the frame sealant is aligned with a to-be-attached product according to human eyes, and then the frame sealant is pressed to the product by sliding tweezers across the frame sealant. However, the above manner not only consumes a lot of manpower, but also cannot guarantee that each piece of frame sealant is attached to the same position. The frame sealant may be misplaced and thus it is difficult to ensure attachment accuracy. Further, when the frame sealant is pressed by the tweezers, the tweezers may slide to a light-emitting area, thereby resulting in defective products.